For all types of substrates, perpendicular magnetic recording (PMR) technology has become more prevalent in magnetic recording media with the goal of increasing areal density. Areal density is generally limited by the media's ability to, at a sufficiently small bit size, write a data bit, read back the same data bit, and maintain the magnetic characteristics of the data bit over time. For magnetic media, these parameters are controlled by the materials coercivity. However, there exists a threshold wherein the coercivity is so high, and the bit size so small, that the writing element must use an impractically high magnetic field to affect change to a data bit. The advent of heat-assisted magnetic recording (HAMR) media addresses this problem by applying heat to a data bit during a write operation to lower the coercivity to a writable level, and then removing the heat to allow the coercivity to return to a high level to keep the data bit stable.
By using HAMR technology, areal density in hard disk drives can be extended beyond 1 Tb/in2. HAMR media generally incorporate a semiconductor laser diode coupled to a waveguide to provide heat energy to the non-volatile recording media during write operations. During the manufacturing process of the HAMR head, the semiconductor laser diode chip is aligned and bonded on a submount chip, sometimes referred to as the Chip-on-Submount-Assembly (COSA). The COSA is then aligned and mounted on a magnetic head slider assembly, with the light emitting end of the laser diode coupling to a waveguide. In order to efficiently deliver laser energy through, the alignment tolerance for the COSA-to-slider mounting process generally is less than 0.5 um at 3-sigma.
The COSA-to-slider mounting process may include a eutectic bonding step. Eutectic bonding incorporates the use of a eutectic alloy deposited on the surfaces of two objects, and then bringing the surfaces of those two objects in contact while applying heat and pressure. The eutectic alloy will liquefy at predetermined heat and pressure combinations, and then re-solidifies once the heat and/or pressure is removed, thus creating a bond between the two objects. One such eutectic bonding process may be used to bond a COSA to a slider by applying a eutectic alloy to a surface of the COSA and/or to an opposite facing surface of a slider, and then bringing the COSA in contact with the slider while applying heat and pressure. In order to stabilize the COSA and the slider during the bonding process, each of the COSA and the slider may be coupled to a carrier using a vacuum mounting process, and the respective carrier may be coupled to an alignment stage, also using a vacuum mount. Conventional bonding processes, however, may result in lowered yield due to misalignment because of lateral sliding forces that are generated when orthogonal pressure is applied to the COSA and slider during bonding. For example, the smooth surfaces on conventional alignment stages and carriers provide minimal lateral resistance when components start to slide. The resulting potential for misalignment results in a lower than desired yield of properly aligned completed COSA-on-slider assemblies.
The figures are not intended to be exhaustive or to limit the invention to the precise form disclosed. It should be understood that the invention can be practiced with modification and alteration, and that the disclosed technology be limited only by the claims and the equivalents thereof.